Though it is 30 years______ we last met, I still remember the scene ______ we got separated on a rainy day.

________ your composition carefully, some spelling mistakes can be avoided.

— Have you been to the Great Wall? —Perhaps not in my memory. ________, it might have been during my early childhood.

 It is fairly common in Africa for there______ a group of expert musicians surrounded by others who also join in the performances.

The time he has devoted in the past ten years ________the disabled is now considered _______of great value.